Here is my idea.
Take 'mechs from the Age of War/Star League era that do not have "Introductory Rules" level variants and build new models that "could" have been used during the Succession Wars using that rules set.
These are 'mechs that could have been secretly horded on backwater planets, salvaged from a forgotten battlefield, or discovered in a cache. However you care to justify their existence, the premise is that they did exist. That they were reconditioned and had their advanced components stripped out or their primitive components upgraded, and then were sent into battle using current (Introductory level/Level 1) technology.
My list of units so far is:
Cestus
Dragoon
Galahad
Jackrabbit
Kyudo
Nightstar
Night Hawk (Added)
Osprey
Ostwar
Rifleman III
Shootist
Sling
Spartan
Spector
Starslayer
Talon
Thunderhawk
Thoughts? Any 'mechs that I missed? Any here that should not be included?
I know some of these chassis are listed as extinct, but the entire premise behind this project is that they actually weren't. That somehow a model or two here and there survived and wound up as a family heirloom, was found in a crashed dropship on the bottom of a lake, or wound up in an unaffiliated mercenary company.
I am going to start posting my variants in the fan design forum in a thread with this title.
http://bg.battletech.com/forums/index.php?topic=58025.0Please feel free to add your own.